The role of the indirect tunneling processes and asymmetry in couplings in orbital Kondo transport through double quantum dots

Abstract

System of two quantum dots attached to external electrodes is considered theoretically in orbital Kondo regime. In general, the double dot system is coupled via both Coulomb interaction and direct hoping. Moreover, the indirect hopping processes between the dots (through the leads) are also taken into account. To investigate system's electronic properties we apply slave-boson mean field (SBMF) technique. With help of the SBMF approach the local density of states for both dots and the transmission (as well as linear and differencial conductance) is calculated. We show that Dicke-and Fano-like line shape may emerge in transport characteristics of the double dot system. Moreover, we observed that these modified Kondo resonances are very susceptible to the change of the indirect coupling's strength. We have also shown that the Kondo temperature become suppressed with increasing asymmetry in the dot-lead couplings when there is no indirect coupling. Moreover, when the indirect coupling is turned on the Kondo temperature becomes suppressed. By allowing a relative sign of the nondiagonal elements of the coupling matrix with left and right electrode, we extend our investigations become more generic. Finally, we have also included the level renormalization effects due to indirect tunneling, which in most papers is not taken into account.

Spin-orbital and spin Kondo effects in parallel coupled quantum dots

“…The off-diagonal elements are usually taken in the form Γ 12 = √ Γ 1 Γ 2 = Γ [21]. The case of common electrodes corresponds to equal diagonal and off-diagonal couplings, we discuss also the case of reduced off-diagonal coupling Γ 12 = qΓ, q ≤ 1 [98]. Fig.…”

Duality in Resistance Switching Behavior of TiO2-Cu2ZnSnS4Device

“…Deposition of a titania nanoparticle (TNP) layer can be used to increase the surface area of T-NTA and has been shown to improve the deposition of the other nanocrystals, for example. 32 Following reported protocol, 33 TNPs were deposited by soaking the annealed titania naotubes in a 0.2 M TiCl 4 ethanolic solution at [65][66][67][68][69][70] • C for 20 min followed by rinsing with ethanol and deionized (DI) water and additional annealing at 450…”

“…30 Hence, the tunneling process for this system was investigated, which can be direct or indirect. 65,66 It is well known that TiO 2 anatase structure has an indirect band gap, while the conduction band maximum at the -point and valence band minimum is located along the (100) direction. 67,68 On the other hand, CZTS is a direct band gap semiconductor and its conduction band minimum and the valence band maximum are aligned and located at the -point.…”

Formation of nonequilibrium steady states in interacting double quantum dots: When coherences dominate the charge distribution

“…For some purposes one may think of the orbital degree of freedom in the spinless double-dot problem as playing a similar role to that of the spin degree of freedom in a conventional single-orbital dot [36][37][38][39]. There is, however, a fundamental difference between the two systems: the coherence between the dots plays a key role in the double dot system, while it is typically zero or vanishes in the steady state of the aforementioned single-dot situations.…”